As others have said, don't take the ship's excursion - go on your own. There will be taxis right at the dock that will take you to the bay, and when you are ready to leave, there will be a line of them waiting to bring you back to the ship.
This isn't the place to snorkel. St. John is great for that, or there is Sapphire Beach, which I hear is gorgeous and has great snorkeling. (Maybe next cruise I will go there!)
Enjoy your cruise!
Mariner of the Seas 3/30/08
"Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover."
Check out my cruise photos: http://community.webshots.com/user/Sheffie100